With the behind-the-ear and in-the-ear hearing devices available on the market it is necessary as a rule to connect an earpiece tailored to the auditory canal of a hearing device wearer to an in-the-ear loudspeaker. There are different solutions for establishing a secure connection depending on the design of the earpiece.
For individually adapted earpieces, also called earmolds, a mold of the wearer's ear is taken and in accordance with this mold a shell or a body is produced in rigid or hard version. The hard version is typically an otoplastic or a plastic shell produced by means of rapid prototyping technology. In these cases a “hard snap-in connection” is selected as the mechanical connection between loudspeaker, also referred to as receiver, and earpiece. FIG. 1 shows a schematic diagram of this “hard-hard connection”. A spherically-shaped hard snap-in element 21 of a loudspeaker 23 can be introduced into an opening 22 of a hard earpiece 24 to form a precise fit. The undercut of the spherically-shaped hard snap-in element 21 means that the snap-in element 21 latches securely into the opening 22. Because of the hardness of the materials the connection elements 21, 22 must be embodied relatively small.
In another solution the earpieces are not individually adapted, but the hearing aid user can select from a limited number of different-sized, flexible earpieces made from a soft material, for example silicone. Different softnesses of earpiece cover the different auditory canal shapes of the hearing aid wearers. Since the respective earpiece does not fit the respective auditory canal exactly, the earpiece is commonly deformed reversibly on insertion into the auditory canal. It must therefore be designed to be as elastic as possible, in order to give a pleasant feeling when being worn. On the other hand the plug-in connection to the loudspeaker must be sufficiently firm to ensure that it is retained securely in the earpiece. This requires a minimum size of loudspeaker snap-in element. FIG. 2 shows this so-called “hard-soft connection” schematically. A spherically-shaped hard snap-in element 21 of a loudspeaker 23 can be introduced into an opening 22 of a soft earpiece 24 to form a precise fit by deforming the latter. Because of the different hardness of the materials the connection elements 21, 22 must be embodied relatively large to hold securely.
A further disadvantage of the “hard-soft connection” is that it can result in wear to the soft material from snapping it onto the hard material. The geometry of the snap-in element must however be designed “aggressively” so as to provide a secure hold. Thus the snap-in connection can no longer hold reliably after a small number of plug-in cycles.
The subsequently-published DE 10 2008 036 258 A1 specifies an earmold for a hearing device with an opening for accepting a snap-in element arranged on a receiver or on a sound tube, with the opening being lined with a hard layer. This offers the advantage of the connection being suitable both for soft and also for hard earmolds. Preferably the snap-in element is embodied in the shape of a sphere. This allows the snap-in element to be embodied very small.